Effects of eccentric training on torque-angular velocity-power characteristics of elbow flexor muscles in older women

The purpose of this study was to investigate the potential of eccentric training to improve elbow flexor muscle power in elderly subjects. Fourteen older female volunteers (age range 60-78 years) were randomly assigned into either a training group (TG) or a control group (CG). For the TG, the 21-session 7-week eccentric training program consisted of 5x6 eccentric muscle actions at 60-100% of concentric three maximal repetitions. Before and after training, maximal elbow flexions were performed against increasing inertia. Maximal isokinetic elbow flexions at four angular velocities (eccentric actions, -60 degrees s(-1), -30 degrees rads(-1); concentric actions, 30, 60 degrees s(-1)) and maximal isometric actions were also performed. Maximal power (Pmax) and an index of maximal shortening velocity (VImax)were determined. For all action conditions, the myoelectric activities of the biceps and the triceps brachii muscles were recorded and quantified as a root mean square (RMS) value. In the TG, maximal torque developed under isometric, isokinetic and inertial conditions increased significantly after training (ranging from 11 to 19%). Pmax and VImax also increased significantly (31.3 and 25.9%, respectively). These parameters remained unchanged in the CG. The RMS activity of the biceps and triceps muscles was not affected by eccentric training for all action conditions excepting the eccentric condition at -30 degrees s(-1) where the RMS activity of the biceps increased significantly. The gains in maximal torque, Pmax and VImax observed after training would result more from intramuscular modifications than from changes in muscular activity, except for eccentric condition at -30 degrees s(-1) where the torque gains could also be partly explained by a reduction in inhibition of the motor unit pool.